The answers to your foolish questions are:
No
No, but usually
Depends on the statute of the state. SYG is effectively an extension of Castle and SD
Yes
In the words of Demastreau: “The uninformed is detected by his answers, the fool by his questions.”
Are you aware that every day, in every major city in the country, charges are not brought, or dismissed by a judge, in assault, battery, manslaughter and other cases by the simple application of justification by reason of self defense?
It has no connection to SYG, Castle Doctrine, or any other recent laws. It has existed forever and needs no other justification.
By the by, when one is on the ground, unable to escape, how can one apply SYG, which is intended to allow self defense when there IS an opportunity to escape.
Conversely, in the same situation, self defense certainly applies.
So, self defense, a doctrine recognized throughout history is foolish in your eyes?